Random pose generator addon ? How can it be done
#i can already tell you you won't like the results.

import math
import bpy
import random
def MoveRandBone(LIMIT1,LIMIT2,BONE_NAME):
    ob = bpy.data.objects['metarig']
    bpy.context.scene.objects.active = ob
    bpy.ops.object.mode_set(mode='POSE')
    BONE = ob.pose.bones[BONE_NAME]
    BONE.rotation_mode = 'XYZ'
    tmpcheck = random.randint(1,3)
    if tmpcheck == 1:
        axis = 'X'
    if tmpcheck == 2:
        axis = 'Y'
    if tmpcheck == 3:
        axis = 'Z'
    tmpangle = random.randint(LIMIT1,LIMIT2)
    angle = tmpangle
    BONE.rotation_euler.rotate_axis(axis, math.radians(angle))
    bpy.ops.object.mode_set(mode='OBJECT')
def cripple():#does everthing
    ob = bpy.context.object
    if ob.type == 'ARMATURE':
        armature = ob.data
        for bone in armature.bones:
            print(bone.name)
            MoveRandBone(300,360,str(bone.name))
def listedlimits():#and since you know what every bone is, you can make your own list and generate a random pose.
    MoveRandBone(350,360,'foot.R')
    MoveRandBone(350,360,'foot.L')
    MoveRandBone(350,360,'shin.R')
listedlimits();

#this is just a terrible way to animate, but can be a lot of fun if you just want to see random effects and apply limits to your bones, note that the
#limits here are not the total limit but the limits as to what can be applied. you are far better off going into riggify and creating your own by lining
#an metarig up. Or by using someone elses human rig.